The objective of the proposed research is to continue our mapping of the avian olfactory system by completing the electrophysiological studies already in progress on the pigeon (Columba livia) and by extending them to two other avian species with larger and smaller olfactory bulbs, respectively, than the pigeon. These two species will be decided upon at the time on the basis of current availability; likely candidates are the mallard duck (Anas platyrhynchos) and the common crow (Corvus brachyrhynchos). Observations now being made on responses evoked in the pigeon's telencephalon by direct electrical stimulation of the ipsilateral olfactory bulb will be supplemented by recording from the same sites after stimulation of 1) the ipsilateral olfactory nerve or 2) the contralacteral olfactory bulb. In addition, the telencephalon and midbrain will be systematically explored following electrical stimulation of the telencephalic areas that we are now identifying as sites of termination of the axons of mitral cells in the olfactory bulb. Results from our electrophysiological experiments now in progress suggest the location of some of the areas where these responses will be found, viz., the sites where long-latency polyphasic responses are obtained following bulbar stimulation, but more extensive exploration must be made both within and beyond the telencephalon and the number of synapses identified. In the other species, telencephalic responses evoked by bulbar stimulation will be recorded. These experiments will increase the range of avian forms examined and, thus, provide some information about the extent to which results obtained with the pigeon can be considered representative of the avian olfactory system.